Ultrahigh density data storage in an organic film with a scanning tunneling microscope

A nanometer-scale recording technique was demonstrated on N-(3-nitrobenzyli dene) p-phenylenediamine (NBPDA) organic thin films with a scanning tunneli ng microscope (STM). NBPDA thin films were fabricated by vacuum thermal dep osition. The results of ultraviolet-visible absorption and infrared transmi ssion spectra showed that the structure of the NBPDA film was the same as t hat of NBPDA crystal. An atomic force microscope was utilized to characteri ze the surface morphology of the NBPDA film. Data were recorded by applying voltage pulses between the tip and the substrate. The current-voltage char acteristics measured by the STM indicated that the local electrical propert y changed from an insulating property into a metallic property after the da ta were written. Data marks, 1.4 nm in diameter, corresponded to a data sto rage density of 10(12) bits/cm(2). A preliminary calculation was presented to explain the recording mechanism. (C) 1999 American Vacuum Society. [S073 4-211X(99)01906-X].